1. Field of the Invention
The invention relates to a method and apparatus for applying a pre-formed decoration to an article by using hydrostatic pressure and by heating the decoration before it is transferred to the article.
2. Background of the Prior Art
U.S. Pat. No. 4,010,057 , corresponding to German Patent No. DE-A- 25 34 640, describes a method and corresponding apparatus for applying a decoration to an article using hydrostatic pressure. This patent is hereby incorporated by reference. However, this patent neither teaches nor suggests heating the decoration before such a decoration is applied to the article.
U.S. Pat. No. 3,867,173 describes a method of decorating objects with wax in which heated wax is dripped upon a liquid surface to form a film and the article to be decorated is then dipped into the liquid thereby receiving the wax film. However, the wax dripped upon the liquid surface is unrestrained and free to assume any shape on the surface of the liquid. For that reason, the appearance of the wax film on the article will be entirely random and unsuitable for situations requiring repetitive applications of a pre-formed decoration.
U.S. Pat. No. 4,348,246 and U.S. Pat. No. 4,388,866 describe transfer printing techniques in which the film with the decoration to be transferred is not placed upon a layer of water but instead is placed upon a layer of granules or a deformable layer of pins.
U.S. Pat. No. 4,436,571 describes a transfer printing technique in which the article to receive a decoration is immersed in a specific way into a flowing liquid with the decoration floating thereupon. The article is presented to the decoration in a continuous movement in the general direction of the liquid flow along a downward path oblique to the surface of the liquid and then along an upward path oblique to the surface of the liquid to provide contact between the decoration and the article.
U.S. Pat. No. 4,407,881, corresponding to DE-A- 32 19 992, describes a transfer printing technique in which the decoration is supported on a layer of a special film made of a hydrophilic, deformable layer which can swell by absorption of water, and a further layer which is placed over the hydrophilic layer and is varyingly permeable to water so that the hydrophilic layer expands to a greater or lesser extent.
U.S. Pat. No. 4,229,239 describes another transfer printing technique in which the decoration is prepared before the transfer by a solvent in order that it detaches itself more easily from the supporting film when transferred onto the article. This activation of the decoration (printing pattern) takes place directly before transferring the film with the decoration to the surface of the water. The film supporting the decoration is water soluble so that, upon contact with the water, the film dissolves and the decoration is then floating on the surface of the water alone (without the film). The decoration is then transferred to the article to be decorated by subsequent immersion of the article.
U.S. Pat. No. 4,231,829 describes a transfer printing technique in which boric acid or a salt thereof is added to a PVA film supporting the decoration on the liquid or to the water on which the decoration floats in order to promote the transfer process.
U.S. Pat. No. 4,269,650 also describes a transfer printing technique utilizing the addition of a solvent in order to make the detachment of the decoration from the supporting film easier.
The solvents provided in the prior art discussed above for activation of the decoration are, for example, pentanes, hexanes, heptanes, octanes, gasoline (petrol) or else aromatic hydrocarbons, such as benzene, toluene, cyclohexane, etc. To promote the activation by means of such solvents, the addition of synthetic resins, such as halogenated vinylchlorides and the like, is also proposed in the cited prior art.
Use of solvents for activation of the decoration is laborious and requires special measures for environmental protection.